docs: def scope_compose(scope, name, sep=private.SCOPE_SEPARATOR):
      """ compose a new scope
  
      :param str scope: current scope
      :param str name: name of next level in scope
      :return the composed scope
      """
  
      if name == None:
          new_scope = scope
      else:
          new_scope = scope if scope else name
  
      if scope and name:
          new_scope = scope + sep + name
  
      return new_scope